The effect of tunnel size, advance rate, and depth of cover on the stand-up time of tunnels in squeezing ground was investigated through a series of 12 physical model tests. The stand-up time, defined as the time elapsed before instability develops, was found to be characterized by increasing deformations and deformation rates rather than a catastrophic collapse of the tunnel. Test results showed a 25% increase in stand-up time was realized by halving the size of the opening (from 5.0 m dia. to 2.4 m dia. when scaled to prototype dimensions) or by decreasing the advance rate by a factor of four (from 1.3 m/hr to 0.3 m/hr for the 5.0 m dia. tunnel). Depth of cover was described in terms of the ratio of confining pressure to material strength. Decreasing the depth (or increasing material strength) by 10% also increased stand-up time by 25%. In order to establish a predictive capability, a constitutive theory describing the time dependent behavior of soft clays has been developed.

  • Corporate Authors:

    University of California, Berkeley

    Institute of Transportation Studies Library
    Berkeley, CA  USA  94720

    Department of Transportation

    Office of University Research, 1200 New Jersey Avenue, SE
    Washington, DC  USA  20590
  • Authors:
    • Myer, L R
    • Brekke, T L
    • Korbin, G E
    • Kavazanjian, E
    • Mitchell, J K
  • Publication Date: 1977-6-30

Media Info

  • Pagination: 208 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00167321
  • Record Type: Publication
  • Source Agency: National Technical Information Service
  • Report/Paper Numbers: DOT-TST-77/59 Final Rpt.
  • Contract Numbers: DOT-OS-50108
  • Files: NTIS, TRIS, USDOT
  • Created Date: Nov 23 1978 12:00AM